The present invention relates generally to the compressor art, and more particularly to a novel and improved cooling system for providing cooling to an oil-flooded air compressor. More specifically, the present invention concerns such an oil cooling system that operates in conjunction with the engine cooling system of a vehicle.
Generally, compressors, such as air compressors, are driven by some external prime mover. This prime mover may be an electric motor or an internal combustion engine. The compressors supply compressed air to a receiver tank from which the compressed air is drawn for usage by various pneumatic devices. Certain portable compressors are packaged within their own utility trailer or are separately mounted on a skid that can be moved to a job site. These compressor units are self-contained in that they include their own prime mover, compressor and cooling system for the compressor.
However, another type of compressor can be driven directly by the engine of a vehicle, such as a truck. More specifically, certain compressor units are driven by a power take-off (PTO) from the vehicle engine or transmission. As shown in FIG. 1, a typical compressor 10 can be mounted to the truck frame. The truck includes an internal combustion engine which provides a motive force through a transmission. A drive shaft from the transmission provides power to the rear drive wheels of the truck. In addition, most truck transmissions include a PTO for providing a source of auxiliary power to be used by an external device. In vehicle mounted air compressor assemblies, the PTO shaft provides power to the compressor unit. Another method of using a truck engine to power the compressor employs a split-shaft device in which a second transmission is mounted in the drive shaft.
During the operation of most air compressors, a great amount of heat is built up in the working components as the air is compressed. In one type of compressor known as a monoscrew compressor, offered by the GrimmerSchmidt Corporation of Franklin, Ind., an axial rotor includes rotor grooves which intermesh with fingers of a pair of oppositely disposed star slides. As the rotor turns, the fingers of the star slides mesh within the rotor grooves trapping air in the grooves and compressing the air as it is pushed toward a discharged port at the end of the rotor. Compressors of this sort are generally oil flooded--that is, oil is injected into the rotor groove just after the star finger has closed an end of the groove. The oil, which can be automatic transmission fluid, seals and lubricates the rotor and the star slide and provides cooling for the working parts of the rotor as well as for the compressed air exiting the compressor. Consequently, it is important that the oil used to lubricate and seal the compressor is cooled to improve the operational characteristics of the compressor and to insure that the compressed air is not too hot for immediate use.
A similar oil flow system can be used for vane, twin-screw, scroll and other rotary and flooded compressors.